Typically, front and back surfaces of a semiconductor wafer are mirror-polished by a plurality of steps. Specifically, the steps mainly include rough polishing for providing a high flatness to a semiconductor wafer and final polishing for reducing surface roughness.
Further, in addition to the front and back surfaces of the semiconductor wafer, a chamfered portion is also mirror-polished to prevent generation of dust from the chamfered portion.
The rough polishing is a double-side simultaneous polishing, in which the semiconductor wafer is set in a carrier and both front and back surfaces of the semiconductor wafer are simultaneously polished. During the double-side simultaneous polishing, the chamfered portion is damaged or dented as a result of the contact of the semiconductor wafer with an inner lateral surface of the carrier. Accordingly, the mirror polishing of the chamfered portion is usually performed after the rough polishing so that possible damage and dent can be removed by the mirror polishing.
However, a soft polishing cloth, which is usually used for a polishing pad for the mirror polishing of the chamfered portion, is unintentionally applied not only to the chamfered portion but also to the surface of the wafer during the mirror polishing of the chamfered portion (hereinafter also referred to as “over-polishing”). As a result of over-polishing, the outer peripheral portion of the wafer is adversely thinned (hereinafter also referred to as “edge roll-off”).
In order to prevent severe edge roll-off due to over-polishing as described above, a method of manufacturing a semiconductor wafer includes: double-side polishing a semiconductor wafer; forming a resin protection film on both front and back surfaces of the semiconductor wafer; mirror-polishing a chamfered portion of the semiconductor wafer; and removing the resin protection film (see, for instance, Patent Literature 1). According to Patent Literature 1, the resin protection film is formed on the front and back surfaces of the semiconductor wafer, thereby suppressing over-polishing of the front and back surfaces during the mirror polishing of the chamfered portion to prevent edge roll-off.